The following Australian provisional patent applications are hereby incorporated by cross reference. For the purposes of location and identification, U.S. Patent applications identified by their U.S. patent application serial numbers (USSN) are listed alongside the Australian applications from which the U.S. patent applications claim the right of priority.
Not applicable.
The present invention relates generally to the field of ink jet printing and in particular, discloses a dual nozzle single horizontal actuator ink jet printing mechanism.
Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimination printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.
In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.
Many different techniques of ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, xe2x80x9cNon-Impact Printing: Introduction and Historical Perspectivexe2x80x9d, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Ink Jet printers themselves come in many different forms. The utilization of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuous ink jet printing including a step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al).
Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectric push mode acuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques which rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constructed space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.
It would be desirable to create a more compact and efficient inkjet printer having an efficient and effective operation in addition to being as compact as possible.
It is an object of the present invention to create a dual nozzle single horizontal actuator inkjet printer having a compact and efficient form of operation.
In accordance with the present invention, there is provided a nozzle arrangement for ejecting fluids from a nozzle chamber the nozzle arrangement comprising: a nozzle chamber having at least two fluid ejection ports defined in the walls of the chamber; a moveable paddle vane located in a plane adjacent the rim of a first one of the fluid ejection apertures; and an actuator mechanism attached to the moveable paddle vane and adapted to move the paddle vane in a first direction do as to cause the ejection of fluid drops from a first fluid ejection port and to further move the paddle vane in a second alternative direction so as to cause the ejection of fluid drops out of a second fluid ejection port.
Preferably, the apparatus further comprises a baffle located between the first and second fluid ejection ports and wherein the paddle vane moving in the first direction causes an increase in pressure of the fluid in the volume adjacent the first port and a simultaneous decrease in pressure of the fluid in the volume adjacent the second port.
Further, the apparatus preferable includes a deepened etched pit below the second fluid ejection port, the baffle and end portion of the moveable paddle vane. Also, the apparatus can include a fluid supply channel connecting the nozzle chamber with a fluid supply for supplying fluid to the nozzle chamber and one surface of the paddle vane includes at least one protrusion, such that, during the movement of the paddle in at least one of the directions, the at least one protrusion mates with a rim of the fluid supply channel so as to restrict the flow of fluid into the fluid supply channel. Also, the moveable paddle vane preferable includes a lip on an end portion adjacent the baffle, the lip substantially abutting the surface of the baffle during operation of the moveable paddle vane.
The walls of the chamber can include at least one smaller aperture interconnecting the nozzle chamber with the ambient atmosphere and of such a dimension that, during normal operation of the paddle vane, the surface tension effects across the smaller aperture results in the meniscus across the smaller aperture remaining substantially close to the smaller aperture results in the meniscus across the smaller aperture remaining substantially close to the smaller aperture or within the nozzle chamber. Preferably, at least one smaller aperture(s) is substantially adjacent to the first one of the fluid ejection ports such that, which ink is ejected from the second fluid ejection port, the meniscus of the first fluid ejection port and the at least one smaller aperture are interconnected within the nozzle chamber. Preferably, each port can include a ribbed rim around the outer surface thereof.
The baffle can include a wall surface having portions spaced at a substantially constant radius from the axis of the second fluid ejection port.
The actuator can comprise a thermal actuator having at least two heater elements with a first of the elements being acutated to cause the paddle vane to move in a first direction and a second heater element being acutated to cause the paddle vane to move in a second direction. Preferably, the heater elements have a high bend efficiency wherein the bend efficiency is defined as:       bend    ⁢          xe2x80x83        ⁢    efficiency    =                                                        Young              '                        ⁢            s            ⁢                          xe2x80x83                        ⁢            Modulus            ⁢                          xe2x80x83                        xc3x97                                                            (                          Coefficient              ⁢                              xe2x80x83                            ⁢              of              ⁢                              xe2x80x83                            ⁢              thermal              ⁢                              xe2x80x83                            ⁢              Expansion                        )                                      Density      xc3x97      Specific      ⁢              xe2x80x83            ⁢      Heat      ⁢              xe2x80x83            ⁢      Capacity      
A suitable material for the heater elements is a copper nickel alloy. The heater elements are preferably arranged on opposite sides of a central arm, the central arm having a low thermal conductivity and the thermal actuator preferably operates in an ambient atmosphere. The central arm can be made from glass.
Preferably, the actuator mechanism is interconnected with the moveable paddle vane through a slot in the wall of the nozzle chamber and includes at least one protrusion portion for minimizing any wicking of the fluid along the actuator mechanism. The protrusion can comprise a cusped rim on the actuator mechanism. The slot connects the internal portions of the nozzle chamber with an external ambient atmosphere and preferably the external surface adjacent the slots comprises a planar or concave surface so as to reduce wicking.
The present invention is suitable for forming an ink jet printhead comprising a plurality of nozzle arrangements as previously described with the fluid ejection apertures grouped together spatially into spaced apart rows and fluid ejected from the fluid ejection apertures of each of the rows in phases. The nozzle arrangements are further grouped into multiple ink colors with each of the nozzle arrangements being supplied with a corresponding ink color.
The array of nozzle chamber can be arranged in a pagewidth printhead and the moveable paddles of each nozzle chamber can be driven in phase.